Normally, primary aromatic amines with an additional free or substituted hydroxyl or amino group in the para or ortho position, diaminopyridine derivatives, heterocyclic hydrazones, 4-amino pyrazole derivatives as well as 2,4,5,6-tetramino pyrimidine and derivatives thereof are employed as the developer components.
Specific exemplary representatives are p-phenylenediamine, p-toluoylenediamine, 2,4,5,6-tetraminopyrimidine, p-amino phenol, N,N-bis(2-hydroxyethyl)-p-phenylenediamine, 2-(2,5-diaminophenyl)ethanol, 2-(2,5-diaminophenoxy)ethanol, 1-phenyl-3-carboxyamido-4-amino-pyrazolone-5,4-amino-3-methylphenol, 2-aminomethyl-4-aminophenol, 2-hydroxymethyl-4-aminophenol, 2-hydroxy-4,5,6-triaminopyrimidine, 2,4-dihydroxy-5,6-diamino pyrimidine, 2,5,6-triamino-4-hydroxypyrimidine and 4,5-diamino-1-(2-hydroxyethyl)pyrazole.
m-Phenylenediamine derivatives, naphthols, resorcinol and resorcinol derivatives, pyrazolones, m-amino phenols and substituted pyridine derivatives are generally used as the coupling components.
Particularly suitable coupling substances are α-naphthol, 1,5-dihydroxynaphthalene, 2,7-dihydroxynaphthalene and 1,7-dihydroxynaphthalene, 5-amino-2-methylphenol, m-amino phenol, resorcinol, resorcinol monomethyl ether, m-phenylenediamine, 2,4-diamino phenoxyethanol, 2-amino-4-(2-hydroxyethylamino)-anisole (Lehmann's Blue), 1-phenyl-3-methylpyrazolone-5,2,4-dichloro-3-aminophenol, 1,3-bis(2,4-diaminophenoxy)propane, 2-chlororesorcinol, 4-chlororesorcinol, 2-chloro-6-methyl-3-amino phenol, 2-methylresorcinol, 5-methylresorcinol, 3-amino-6-methoxy-2-methylamino pyridine and 3,5-diamino-2,6-dimethoxypyridine.
Indeed, with the oxidation dyes, intensive colorations can be achieved with good fastness characteristics, but the development of the color normally occurs in the presence of oxidizing agents, such as e.g., H2O2, which in some cases can result in damage to the fibers. Furthermore, some oxidation dye precursors or certain mixtures of oxidation dye precursors sometimes have a sensitizing effect on people with delicate skin. Substantive dyes are applied under more gentle conditions, but their disadvantage is that the colorations often possess only inadequate fastness characteristics.
An advantage when dyeing hair with substantive dyes lies principally in the vibrant fashion shades that can be achieved with this dyeing method. For consumers with darker hair colorations, however, a lightening has to take place at the same time as the fashion shade dyeing, thereby lightening the natural hair color by destroying the melanin pigments of the original hair and thus lending more brilliance to the added dyes. The use of hydrogen peroxide by itself suffices for a slight lightening, however a combination of hydrogen peroxide and persulfate salts is usually added for stronger lightening over a plurality of nuances. Up to now, the person skilled in the art is aware of very few brilliant dyes from the prior art which are sufficiently stable towards hydrogen peroxide/persulfate salts and which simultaneously possess good applications-related properties.